⚡ CI/CD with Docker + GitHub Actions | Debugging Docker Push Failures

DevOps Labs — Real-World CI/CD Debugging That Engineers Must Know

Author

Arbaz M
October 02, 2025

🎯 Why Docker Push Failures Matter

Every DevOps engineer eventually sees this error:

You build a Docker image.
You try to push it to Docker Hub.
❌ denied: requested access to the resource is denied

Why? Because the image wasn’t tagged with the repository name.

This simple mistake breaks pipelines every day — and knowing how to debug it separates engineers who panic from those who keep CI/CD flowing.

▶️ What You’ll Learn in This Video

In this step-by-step hands-on demo, I break down: [YouTube Link]

📌 CI/CD Basics with Docker

  • Building & tagging Docker images correctly

  • Pushing to Docker Hub via GitHub Actions

  • Automating deployment with Jenkins pipelines

📌 Debugging the Mistake

  • Wrong tag: flask-app:v1 → ❌ push denied

  • Correct tag: username/flask-app:v1 → ✅ push works

📌 The Fix

  • Always tag images with registry + repo + version

  • Validate image names before pushing

  • Update GitHub Actions + Jenkins pipeline to handle proper tags

📌 Best Practices

  • Never rely on just latest in production

  • Keep versioning consistent across pipelines

  • Test builds locally before pushing to CI/CD

👉 Watch the full video here: [YouTube Link]
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🛠 Takeaway Example Command

❌ Wrong: 

docker build -t flask-app:v1 .
docker push flask-app:v1

✅ Correct: 

docker build -t mydockerhub/flask-app:v1 .
docker push mydockerhub/flask-app:v1

💡 Always include the repo name before pushing.

💡 Why This Guide Stands Out

  • Real-world focus → I don’t just show a working pipeline; I simulate the push failure you’ll hit in production.

  • Debug-driven → You’ll see the actual denied error and the fix.

  • Production-ready → By the end, you’ll know how to structure CI/CD with proper image tagging.

This isn’t just Docker theory — it’s CI/CD you’ll actually run at work.

👋 Final Note

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